Limitations and Opportunities of Transcutaneous Bilirubin Measurements

Bosschaart, Nienke; Kok, Joke H.; Newsum, Astrid M.; Ouweneel, Dagmar M.; Mentink, Rosaline; Leeuwen, Ton G. van; Aalders, Maurice C. G.

doi:10.1542/peds.2011-2586

Cited by 68 publications

(43 citation statements)

References 32 publications

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“…5 It may be argued that the divergence between TcB and TSB should not be unexpected after all, because the former measures the extravascular rather than the intravascular bilirubin concentration, and possibly better reflects the risk of kernicterus. 35 However, additional studies are warranted to establish more precisely the clinical value of TcB as a predictor of kernicterus.…”

Section: Figurementioning

confidence: 99%

Differences Between Transcutaneous and Serum Bilirubin Measurements in Black African Neonates

2016

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BACKGROUND AND OBJECTIVE: Transcutaneous bilirubin (TcB) correlates positively with total serum bilirubin (TSB) across different racial populations. However, little is known about the pattern of divergence between TcB and TSB at individual patient-level and the relationship with TcB measuring techniques among African neonates. This study, therefore, investigates TcB-TSB discrepancies and the contribution of 2 models of transcutaneous bilirubinometers to the observed divergence in a black African population.

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Section: Figurementioning

confidence: 99%

Differences Between Transcutaneous and Serum Bilirubin Measurements in Black African Neonates

2016

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“…Enabled by advances in physical optics and electronics, the optical properties of human skin have become well described (1,2,(9)(10)(11)(12)(13)(14). This has resulted in a model of skin optics that has led to improvements in devices such as transcutaneous bilirubinometers (2,9,14,21,37). Those features of this model for skin optics germane to the spectral region (400-520 nm) prescribed for jaundice therapy are reviewed here.…”

Section: Model and Calculationsmentioning

confidence: 99%

The effect of hematocrit on the efficacy of phototherapy for neonatal jaundice

et al. 2013

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Background:The therapeutic phototherapy action spectrum ranges from 420 to 500 nm. However, a recent report of improved efficacy of fluorescent "turquoise" light (~490 nm) as compared with blue light (~450 nm) underscores the need to define an optimal action spectrum for precision-targeted phototherapy using very narrow wavelength ranges. Methods: We used a current semi-empirical model of the optical properties of skin for robust calculations of the fraction of light absorbed by bilirubin at various wavelengths that could be confounded by hemoglobin (Hb), melanin, and skin thickness. Applying assumptions regarding the wavelength dependence of bilirubin photochemistry, "action spectra" were assembled from the calculated values. results: All the calculated action spectra displayed a peak between 472 and 480 nm (most at 476 nm), which is a significant shift from the well-reported 460 nm absorption peak of bilirubin. Of note, the relative amplitudes of the action spectra showed an inverse relationship with hematocrit (Hct). conclusion: We speculate that a narrow range of light at 476 nm would be 60% more effective than blue (broadband) fluorescent lamps. Because Hb serves as a major competitor of bilirubin for light absorption, the calculations also predict that the efficacy of phototherapy is dependent on the Hct. A high Hct could reduce therapeutic efficiency. a n in vivo model to better define the optimal wavelength range for precision-targeted phototherapy has been elusive. Advances in understanding of skin optical properties have provided an optical model of neonatal skin in the therapeutic range (400-520 nm) that allows facile calculation of the influences of skin structure, melanin pigmentation, and cutaneous hemoglobin (Hb) on the action spectrum for phototherapy. Of these, Hb absorbs most of the visible light in the skin (1,2). As a result, competition from Hb with bilirubin for light should strongly affect the wavelength region of light that is most effective for phototherapy of neonatal jaundice. Although Hb competition has been recognized and used, in part, to predict the action spectrum for phototherapy (3,4), explicit reference to Hb competition appears to be absent from the recent literature. The reports of clinical studies showing that blue-green or green light may be more effective than blue light (5,6) generally rationalize these observations on the general notion that the longer wavelengths "penetrate deeper into the skin" without specific reference to Hb absorbance.Furthermore, significant competition for light by skin Hb also implies that the hematocrit (Hct) may in turn affect the efficacy of phototherapy. This possibility was recognized in 1974 by Lucey and Hewitt (7), who conjectured that the Hct "may be a contributing factor to the differences in response of serum bilirubin to light that one observes in different infants. " They observed in in vitro irradiation studies that changes in the Hct affect diazo-reactive bilirubin disappearance in blood. Almost a decade elapsed before a clinical st...

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“…These could be confounding factors, in particular albuminemia and capillary pH which are the main determinants for bilirubin extravasation and skin deposition, and thus for TcB. Indeed, it must be kept in mind that while TcB is strongly related to TSB, it corresponds to extravascular rather than intravascular bilirubin (bilirubin extravasated and deposited in the skin), and is thus a basically distinct variable from TSB [21]. …”

Section: Discussionmentioning

confidence: 99%

Diagnosis Accuracy of Transcutaneous Bilirubinometry in Very Preterm Newborns

Rubio¹,

Epiard

Gebus

et al. 2016

Neonatology

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Background: Transcutaneous bilirubin (TcB) is a validated test for systematic screening of neonatal hyperbilirubinemia and monitoring term and near-term infants under phototherapy. Objectives: To evaluate TcB diagnostic accuracy for very preterm neonates. Methods: Total serum bilirubin (TSB) and TcB measurements were performed prospectively in a multicenter sample of newborns <30 weeks of gestational age (GA). TcB sensitivity, specificity, predictive values, and likelihood ratios for the detection of neonates requiring phototherapy were calculated over the first 15 days of life, with or without phototherapy, with the expectation of achieving a detection rate of hyperbilirubinemia of over 95%. The potential influence of neonatal characteristics on the discordance between TcB and TSB in very preterm newborns was analyzed using multivariate multilevel logistic regression analyses. Results: Altogether, 481 measurements were analyzed in 167 preterm patients. Mean GA was 27.6 ± 1.6 weeks. The rates of newborns requiring phototherapy were 52% in the first 3 days, 16% from the 4th to the 7th day, and 2% during the second week. Diagnostic performance was similar among babies with or without phototherapy. TcB sensitivity decreased over time from 100% (93.9-100.0) to 50% (1.3-98.7). Specificity showed an inverse evolution from 14.8% (7.0-26.2) to 80.7% (72.2-89.2). The best performance was that of negative predictive values which varied from 95.5 to 100.0. False negatives were rare throughout the study (0.8% of measurements). In a multivariate analysis, the only factor significantly influencing discordance between TcB and TSB was postnatal age. We did not find any impact of GA and skin color. Conclusion: Among very preterm babies, TcB measurements might be useful for screening for neonatal jaundice in the first 2 weeks of life. In case of a TcB value below the phototherapy threshold, invasive TSB quantification could be unnecessary, with potential avoidance of blood drawing.

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Limitations and Opportunities of Transcutaneous Bilirubin Measurements

Cited by 68 publications

References 32 publications

Differences Between Transcutaneous and Serum Bilirubin Measurements in Black African Neonates

Differences Between Transcutaneous and Serum Bilirubin Measurements in Black African Neonates

The effect of hematocrit on the efficacy of phototherapy for neonatal jaundice

Diagnosis Accuracy of Transcutaneous Bilirubinometry in Very Preterm Newborns

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